Introduction To GI Physiology PDF
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Eastern Mediterranean University
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Summary
This document provides a general introduction to gastrointestinal physiology. It covers topics such as digestive system processes, secretions, motility, and the regulation of GI function. It is suitable for undergraduate-level study on human biology topics.
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General Principles of Gastrointestinal Function Dr. Alper YILDIRIM [email protected] Objectives: To comprehend the general structure-function relationship of the alimentary tract To differentiate between endocrine, paracrine and neurocri...
General Principles of Gastrointestinal Function Dr. Alper YILDIRIM [email protected] Objectives: To comprehend the general structure-function relationship of the alimentary tract To differentiate between endocrine, paracrine and neurocrine functions To briefly review the major hormones, neurotransmitters and paracrine factors Aim To obtain a general understanding of the gastrointestinal organization and related functions. The Digestive System Basic processes of the digestive system The digestive system performs six basic processes: ingestion, secretion, motility, digestion, absorption, and defecation. Basic processes of the digestive system Distension Presence of food Osmolarity Acid Secretion of digestive juices Organ Exocrine Secretions Mouth Lingual lipase Salivary amylase Lysozyme Water, electrolytes Esophagus Mucus Stomach HCl Pepsin Mucus, Mucin Pepsin Gastric lipase Intrinsic factor Liver Bile Salts Bicarbonate Organic waste products Pancreas Proteases (Trypsin, chymotrypsin) Pancreatic Lipase Amylase Small Intestine Enzymes and mucus Salt and Water Large Intestine Mucus Basic processes of the digestive system Ingestion Motility Slow waves are generated in interstitial cells of Cajal Slow waves are spontaneous depolarizations in GI smooth muscle. Motility Peristaltic contractions are responsible for Segmental contractions are responsible for forward movement. mixing. Regulation of GI Function Regulation of GI Function Enteric Nervous System Autonomic Nervous System Regulation of GI Function Organization of the enteric nervous system Distension Presence of food Osmolarity Acid Regulation of GI Function Cephalic and gastric phase reflexes The GI Hormones Digestive Process Gastric Secretions Integration of cephalic and gastric phase secretion Digestion & Absorbtion Digestion and absorption of Fats Digestion & Absorbtion Digestion and absorption of Carbohydrates Carbohydrate absorption in the small intestine Carbohydrates break down into monosaccharides. Digestion & Absorbtion Digestion and absorption of Proteins The Colonic Phase The large intestine is primarily a drying and storage organ. Haustral contractions slowly shuffle the colonic contents back and forth. Mass movements propel feces long distances. Feces are eliminated by the defecation reflex. Constipation occurs when the feces become too dry. Intestinal gases are absorbed or expelled. Large-intestine secretion is entirely protective. The colon contains myriad beneficial bacteria. You are responsible Guyton & Hall Textbook of Medical Physiology 13th Edition Chapter 63